Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
The loading capabilities of rotor blades and wind turbines in general is of concern during wind turbine design and operation, especially as wind turbine and corresponding rotor blade sizes are increased. High system loads generally lead to increased component size, weight, and cost, which affect the efficiency, performance, and profitability of the wind turbine.
Attempts have been made to reduce rotor blade loading. However, a competing concern when attempting to reduce rotor blade loading is the aerodynamic performance of the rotor blades. In many cases, critical design load capabilities for rotor blades are driven by the loads that are generated when the rotor blades are operating off-design, such as near or within stall regions. A stall region is generally a region wherein changes in the lift coefficient based on changes in the angle of attack of a rotor blade are relatively strong. In a graphical representation of lift coefficient versus angle of attack, for example, stall regions are regions wherein there are strong slopes and changes in slopes. It would thus be desirable to reduce off-design loading while minimizing or eliminating any effects to on-design performance of the rotor blades.
Accordingly, improved wind turbine rotor blades are desired in the art. In particular, rotor blades with off-design load reduction capabilities that have minimal or no on-design performance effects would be advantageous. Additionally, such rotor blade designs in both new construction and retrofit scenarios are desired.